It is well known that industrial gas turbine and aircraft engine shrouds operate in a high temperature environment and require cooling methods to obtain a useful design life cycle. An alternative to using a metal shroud with cooling air is to use a CMC material for the shroud, thus eliminating the required cooling of the shroud due to the CMC's superior temperature capability over metal.
Prior attempts to solve this problem have been made using conventional metal seals or complex assemblies. For example, one approach has been to use multiple pins to hold the CMC or to use hooks formed in the CMC component. Other prior art uses a CMC bonded to a ceramic core with pins going through the core.
These arrangements utilizing pins have two distinct disadvantages, namely (1) additional cooling air is required to maintain design life of the seal, and (2) higher cost due to the use of expensive high temperature custom made metal pins. Metal pins at the flow-path also require cooling air to meet the required design life, thus reducing the benefit of the CMC.
A more effective way of mounting the CMC shroud to the outer metal shroud and preventing hot gases from contacting the metal outer shroud is desirable. The present invention seeks to satisfy that desire.